Commit | Line | Data |
---|---|---|
2592e6c0 JH |
1 | /* |
2 | * PDKIM - a RFC4871 (DKIM) implementation | |
3 | * | |
f9ba5e22 | 4 | * Copyright (C) 1995 - 2018 Exim maintainers |
2592e6c0 | 5 | * |
d73e45df | 6 | * signing/verification interface |
2592e6c0 JH |
7 | */ |
8 | ||
9 | #include "../exim.h" | |
260958d6 JH |
10 | #include "crypt_ver.h" |
11 | #include "signing.h" | |
12 | ||
13 | ||
14 | #ifdef MACRO_PREDEF | |
15 | # include "../macro_predef.h" | |
16 | ||
17 | void | |
18 | features_crypto(void) | |
19 | { | |
20 | # ifdef SIGN_HAVE_ED25519 | |
21 | builtin_macro_create(US"_CRYPTO_SIGN_ED25519"); | |
22 | # endif | |
23 | # ifdef EXIM_HAVE_SHA3 | |
24 | builtin_macro_create(US"_CRYPTO_HASH_SHA3"); | |
25 | # endif | |
26 | } | |
27 | #else | |
2592e6c0 | 28 | |
260958d6 | 29 | #ifndef DISABLE_DKIM /* rest of file */ |
2592e6c0 | 30 | |
01603eec JH |
31 | #ifdef DISABLE_TLS |
32 | # error Must no DISABLE_TLS, for DKIM | |
2592e6c0 JH |
33 | #endif |
34 | ||
2592e6c0 JH |
35 | |
36 | /******************************************************************************/ | |
d73e45df | 37 | #ifdef SIGN_GNUTLS |
286b9d5f JH |
38 | # define EXIM_GNUTLS_LIBRARY_LOG_LEVEL 3 |
39 | ||
40 | ||
41 | /* Logging function which can be registered with | |
42 | * gnutls_global_set_log_function() | |
43 | * gnutls_global_set_log_level() 0..9 | |
44 | */ | |
45 | #if EXIM_GNUTLS_LIBRARY_LOG_LEVEL >= 0 | |
46 | static void | |
47 | exim_gnutls_logger_cb(int level, const char *message) | |
48 | { | |
49 | size_t len = strlen(message); | |
50 | if (len < 1) | |
51 | { | |
52 | DEBUG(D_tls) debug_printf("GnuTLS<%d> empty debug message\n", level); | |
53 | return; | |
54 | } | |
55 | DEBUG(D_tls) debug_printf("GnuTLS<%d>: %s%s", level, message, | |
56 | message[len-1] == '\n' ? "" : "\n"); | |
57 | } | |
58 | #endif | |
59 | ||
60 | ||
2592e6c0 JH |
61 | |
62 | void | |
9b2583c4 | 63 | exim_dkim_init(void) |
2592e6c0 | 64 | { |
286b9d5f JH |
65 | #if EXIM_GNUTLS_LIBRARY_LOG_LEVEL >= 0 |
66 | DEBUG(D_tls) | |
67 | { | |
68 | gnutls_global_set_log_function(exim_gnutls_logger_cb); | |
69 | /* arbitrarily chosen level; bump upto 9 for more */ | |
70 | gnutls_global_set_log_level(EXIM_GNUTLS_LIBRARY_LOG_LEVEL); | |
71 | } | |
72 | #endif | |
2592e6c0 JH |
73 | } |
74 | ||
75 | ||
76 | /* accumulate data (gnutls-only). String to be appended must be nul-terminated. */ | |
acec9514 JH |
77 | gstring * |
78 | exim_dkim_data_append(gstring * g, uschar * s) | |
2592e6c0 | 79 | { |
acec9514 | 80 | return string_cat(g, s); |
2592e6c0 JH |
81 | } |
82 | ||
83 | ||
84 | ||
85 | /* import private key from PEM string in memory. | |
86 | Return: NULL for success, or an error string */ | |
87 | ||
88 | const uschar * | |
617d3932 | 89 | exim_dkim_signing_init(const uschar * privkey_pem, es_ctx * sign_ctx) |
2592e6c0 | 90 | { |
cb78c1a8 | 91 | gnutls_datum_t k = { .data = (void *)privkey_pem, .size = Ustrlen(privkey_pem) }; |
286b9d5f | 92 | gnutls_x509_privkey_t x509_key; |
c59b09dc | 93 | const uschar * where; |
2592e6c0 JH |
94 | int rc; |
95 | ||
c59b09dc | 96 | if ( (where = US"internal init", rc = gnutls_x509_privkey_init(&x509_key)) |
286b9d5f | 97 | || (rc = gnutls_privkey_init(&sign_ctx->key)) |
c59b09dc JH |
98 | || (where = US"privkey PEM-block import", |
99 | rc = gnutls_x509_privkey_import(x509_key, &k, GNUTLS_X509_FMT_PEM)) | |
100 | || (where = US"internal privkey transfer", | |
101 | rc = gnutls_privkey_import_x509(sign_ctx->key, x509_key, 0)) | |
2592e6c0 | 102 | ) |
c59b09dc | 103 | return string_sprintf("%s: %s", where, gnutls_strerror(rc)); |
286b9d5f JH |
104 | |
105 | switch (rc = gnutls_privkey_get_pk_algorithm(sign_ctx->key, NULL)) | |
106 | { | |
107 | case GNUTLS_PK_RSA: sign_ctx->keytype = KEYTYPE_RSA; break; | |
108 | #ifdef SIGN_HAVE_ED25519 | |
109 | case GNUTLS_PK_EDDSA_ED25519: sign_ctx->keytype = KEYTYPE_ED25519; break; | |
110 | #endif | |
111 | default: return rc < 0 | |
112 | ? CUS gnutls_strerror(rc) | |
113 | : string_sprintf("Unhandled key type: %d '%s'", rc, gnutls_pk_get_name(rc)); | |
114 | } | |
2592e6c0 JH |
115 | |
116 | return NULL; | |
117 | } | |
118 | ||
119 | ||
120 | ||
121 | /* allocate mem for signature (when signing) */ | |
286b9d5f | 122 | /* hash & sign data. No way to do incremental. |
2592e6c0 JH |
123 | |
124 | Return: NULL for success, or an error string */ | |
125 | ||
126 | const uschar * | |
d73e45df | 127 | exim_dkim_sign(es_ctx * sign_ctx, hashmethod hash, blob * data, blob * sig) |
2592e6c0 | 128 | { |
286b9d5f | 129 | gnutls_datum_t k_data = { .data = data->data, .size = data->len }; |
d73e45df | 130 | gnutls_digest_algorithm_t dig; |
286b9d5f | 131 | gnutls_datum_t k_sig; |
2592e6c0 | 132 | int rc; |
2592e6c0 | 133 | |
d73e45df JH |
134 | switch (hash) |
135 | { | |
136 | case HASH_SHA1: dig = GNUTLS_DIG_SHA1; break; | |
137 | case HASH_SHA2_256: dig = GNUTLS_DIG_SHA256; break; | |
138 | case HASH_SHA2_512: dig = GNUTLS_DIG_SHA512; break; | |
139 | default: return US"nonhandled hash type"; | |
140 | } | |
141 | ||
286b9d5f JH |
142 | if ((rc = gnutls_privkey_sign_data(sign_ctx->key, dig, 0, &k_data, &k_sig))) |
143 | return CUS gnutls_strerror(rc); | |
2592e6c0 | 144 | |
286b9d5f | 145 | /* Don't care about deinit for the key; shortlived process */ |
2592e6c0 | 146 | |
286b9d5f JH |
147 | sig->data = k_sig.data; |
148 | sig->len = k_sig.size; | |
149 | return NULL; | |
2592e6c0 JH |
150 | } |
151 | ||
152 | ||
153 | ||
286b9d5f | 154 | /* import public key (from blob in memory) |
2592e6c0 JH |
155 | Return: NULL for success, or an error string */ |
156 | ||
157 | const uschar * | |
286b9d5f | 158 | exim_dkim_verify_init(blob * pubkey, keyformat fmt, ev_ctx * verify_ctx) |
2592e6c0 JH |
159 | { |
160 | gnutls_datum_t k; | |
161 | int rc; | |
162 | const uschar * ret = NULL; | |
163 | ||
d73e45df | 164 | gnutls_pubkey_init(&verify_ctx->key); |
286b9d5f JH |
165 | k.data = pubkey->data; |
166 | k.size = pubkey->len; | |
2592e6c0 | 167 | |
286b9d5f JH |
168 | switch(fmt) |
169 | { | |
170 | case KEYFMT_DER: | |
171 | if ((rc = gnutls_pubkey_import(verify_ctx->key, &k, GNUTLS_X509_FMT_DER))) | |
48224640 | 172 | ret = US gnutls_strerror(rc); |
286b9d5f JH |
173 | break; |
174 | #ifdef SIGN_HAVE_ED25519 | |
175 | case KEYFMT_ED25519_BARE: | |
176 | if ((rc = gnutls_pubkey_import_ecc_raw(verify_ctx->key, | |
177 | GNUTLS_ECC_CURVE_ED25519, &k, NULL))) | |
48224640 | 178 | ret = US gnutls_strerror(rc); |
286b9d5f JH |
179 | break; |
180 | #endif | |
181 | default: | |
182 | ret = US"pubkey format not handled"; | |
183 | break; | |
184 | } | |
2592e6c0 JH |
185 | return ret; |
186 | } | |
187 | ||
188 | ||
286b9d5f JH |
189 | /* verify signature (of hash if RSA sig, of data if EC sig. No way to do incremental) |
190 | (given pubkey & alleged sig) | |
2592e6c0 JH |
191 | Return: NULL for success, or an error string */ |
192 | ||
193 | const uschar * | |
d73e45df | 194 | exim_dkim_verify(ev_ctx * verify_ctx, hashmethod hash, blob * data_hash, blob * sig) |
2592e6c0 | 195 | { |
286b9d5f JH |
196 | gnutls_datum_t k = { .data = data_hash->data, .size = data_hash->len }; |
197 | gnutls_datum_t s = { .data = sig->data, .size = sig->len }; | |
2592e6c0 JH |
198 | int rc; |
199 | const uschar * ret = NULL; | |
200 | ||
286b9d5f JH |
201 | #ifdef SIGN_HAVE_ED25519 |
202 | if (verify_ctx->keytype == KEYTYPE_ED25519) | |
d73e45df | 203 | { |
286b9d5f JH |
204 | if ((rc = gnutls_pubkey_verify_data2(verify_ctx->key, |
205 | GNUTLS_SIGN_EDDSA_ED25519, 0, &k, &s)) < 0) | |
48224640 | 206 | ret = US gnutls_strerror(rc); |
d73e45df | 207 | } |
286b9d5f JH |
208 | else |
209 | #endif | |
210 | { | |
211 | gnutls_sign_algorithm_t algo; | |
212 | switch (hash) | |
213 | { | |
214 | case HASH_SHA1: algo = GNUTLS_SIGN_RSA_SHA1; break; | |
215 | case HASH_SHA2_256: algo = GNUTLS_SIGN_RSA_SHA256; break; | |
216 | case HASH_SHA2_512: algo = GNUTLS_SIGN_RSA_SHA512; break; | |
217 | default: return US"nonhandled hash type"; | |
218 | } | |
d73e45df | 219 | |
286b9d5f | 220 | if ((rc = gnutls_pubkey_verify_hash2(verify_ctx->key, algo, 0, &k, &s)) < 0) |
48224640 | 221 | ret = US gnutls_strerror(rc); |
286b9d5f | 222 | } |
2592e6c0 | 223 | |
d73e45df | 224 | gnutls_pubkey_deinit(verify_ctx->key); |
2592e6c0 JH |
225 | return ret; |
226 | } | |
227 | ||
228 | ||
229 | ||
230 | ||
d73e45df | 231 | #elif defined(SIGN_GCRYPT) |
2592e6c0 | 232 | /******************************************************************************/ |
d73e45df | 233 | /* This variant is used under pre-3.0.0 GnuTLS. Only rsa-sha1 and rsa-sha256 */ |
2592e6c0 JH |
234 | |
235 | ||
236 | /* Internal service routine: | |
237 | Read and move past an asn.1 header, checking class & tag, | |
238 | optionally returning the data-length */ | |
239 | ||
240 | static int | |
241 | as_tag(blob * der, uschar req_cls, long req_tag, long * alen) | |
242 | { | |
243 | int rc; | |
244 | uschar tag_class; | |
245 | int taglen; | |
246 | long tag, len; | |
247 | ||
286b9d5f JH |
248 | debug_printf_indent("as_tag: %02x %02x %02x %02x\n", |
249 | der->data[0], der->data[1], der->data[2], der->data[3]); | |
2592e6c0 JH |
250 | |
251 | if ((rc = asn1_get_tag_der(der->data++, der->len--, &tag_class, &taglen, &tag)) | |
252 | != ASN1_SUCCESS) | |
253 | return rc; | |
254 | ||
255 | if (tag_class != req_cls || tag != req_tag) return ASN1_ELEMENT_NOT_FOUND; | |
256 | ||
257 | if ((len = asn1_get_length_der(der->data, der->len, &taglen)) < 0) | |
258 | return ASN1_DER_ERROR; | |
259 | if (alen) *alen = len; | |
260 | ||
6e4aaa85 | 261 | /* debug_printf_indent("as_tag: tlen %d dlen %d\n", taglen, (int)len); */ |
2592e6c0 JH |
262 | |
263 | der->data += taglen; | |
264 | der->len -= taglen; | |
265 | return rc; | |
266 | } | |
267 | ||
268 | /* Internal service routine: | |
269 | Read and move over an asn.1 integer, setting an MPI to the value | |
270 | */ | |
271 | ||
272 | static uschar * | |
273 | as_mpi(blob * der, gcry_mpi_t * mpi) | |
274 | { | |
275 | long alen; | |
276 | int rc; | |
277 | gcry_error_t gerr; | |
278 | ||
286b9d5f JH |
279 | debug_printf_indent("%s\n", __FUNCTION__); |
280 | ||
2592e6c0 JH |
281 | /* integer; move past the header */ |
282 | if ((rc = as_tag(der, 0, ASN1_TAG_INTEGER, &alen)) != ASN1_SUCCESS) | |
283 | return US asn1_strerror(rc); | |
284 | ||
285 | /* read to an MPI */ | |
286 | if ((gerr = gcry_mpi_scan(mpi, GCRYMPI_FMT_STD, der->data, alen, NULL))) | |
287 | return US gcry_strerror(gerr); | |
288 | ||
289 | /* move over the data */ | |
290 | der->data += alen; der->len -= alen; | |
291 | return NULL; | |
292 | } | |
293 | ||
294 | ||
295 | ||
296 | void | |
9b2583c4 | 297 | exim_dkim_init(void) |
2592e6c0 JH |
298 | { |
299 | /* Version check should be the very first call because it | |
300 | makes sure that important subsystems are initialized. */ | |
301 | if (!gcry_check_version (GCRYPT_VERSION)) | |
302 | { | |
303 | fputs ("libgcrypt version mismatch\n", stderr); | |
304 | exit (2); | |
305 | } | |
306 | ||
307 | /* We don't want to see any warnings, e.g. because we have not yet | |
308 | parsed program options which might be used to suppress such | |
309 | warnings. */ | |
310 | gcry_control (GCRYCTL_SUSPEND_SECMEM_WARN); | |
311 | ||
312 | /* ... If required, other initialization goes here. Note that the | |
313 | process might still be running with increased privileges and that | |
314 | the secure memory has not been initialized. */ | |
315 | ||
316 | /* Allocate a pool of 16k secure memory. This make the secure memory | |
317 | available and also drops privileges where needed. */ | |
318 | gcry_control (GCRYCTL_INIT_SECMEM, 16384, 0); | |
319 | ||
320 | /* It is now okay to let Libgcrypt complain when there was/is | |
321 | a problem with the secure memory. */ | |
322 | gcry_control (GCRYCTL_RESUME_SECMEM_WARN); | |
323 | ||
324 | /* ... If required, other initialization goes here. */ | |
325 | ||
326 | /* Tell Libgcrypt that initialization has completed. */ | |
327 | gcry_control (GCRYCTL_INITIALIZATION_FINISHED, 0); | |
328 | ||
329 | return; | |
330 | } | |
331 | ||
332 | ||
333 | ||
334 | ||
335 | /* Accumulate data (gnutls-only). | |
336 | String to be appended must be nul-terminated. */ | |
337 | ||
acec9514 JH |
338 | gstring * |
339 | exim_dkim_data_append(gstring * g, uschar * s) | |
2592e6c0 | 340 | { |
acec9514 | 341 | return g; /*dummy*/ |
2592e6c0 JH |
342 | } |
343 | ||
344 | ||
345 | ||
346 | /* import private key from PEM string in memory. | |
286b9d5f | 347 | Only handles RSA keys. |
2592e6c0 JH |
348 | Return: NULL for success, or an error string */ |
349 | ||
350 | const uschar * | |
617d3932 | 351 | exim_dkim_signing_init(const uschar * privkey_pem, es_ctx * sign_ctx) |
2592e6c0 JH |
352 | { |
353 | uschar * s1, * s2; | |
354 | blob der; | |
355 | long alen; | |
356 | int rc; | |
357 | ||
9b2583c4 | 358 | /*XXX will need extension to _spot_ as well as handle a |
286b9d5f JH |
359 | non-RSA key? I think... |
360 | So... this is not a PrivateKeyInfo - which would have a field | |
361 | identifying the keytype - PrivateKeyAlgorithmIdentifier - | |
362 | but a plain RSAPrivateKey (wrapped in PEM-headers. Can we | |
363 | use those as a type tag? What forms are there? "BEGIN EC PRIVATE KEY" (cf. ec(1ssl)) | |
364 | ||
365 | How does OpenSSL PEM_read_bio_PrivateKey() deal with it? | |
366 | gnutls_x509_privkey_import() ? | |
367 | */ | |
9b2583c4 | 368 | |
2592e6c0 JH |
369 | /* |
370 | * RSAPrivateKey ::= SEQUENCE | |
371 | * version Version, | |
372 | * modulus INTEGER, -- n | |
373 | * publicExponent INTEGER, -- e | |
374 | * privateExponent INTEGER, -- d | |
375 | * prime1 INTEGER, -- p | |
376 | * prime2 INTEGER, -- q | |
377 | * exponent1 INTEGER, -- d mod (p-1) | |
378 | * exponent2 INTEGER, -- d mod (q-1) | |
379 | * coefficient INTEGER, -- (inverse of q) mod p | |
380 | * otherPrimeInfos OtherPrimeInfos OPTIONAL | |
286b9d5f JH |
381 | |
382 | * ECPrivateKey ::= SEQUENCE { | |
383 | * version INTEGER { ecPrivkeyVer1(1) } (ecPrivkeyVer1), | |
384 | * privateKey OCTET STRING, | |
385 | * parameters [0] ECParameters {{ NamedCurve }} OPTIONAL, | |
386 | * publicKey [1] BIT STRING OPTIONAL | |
387 | * } | |
388 | * Hmm, only 1 useful item, and not even an integer? Wonder how we might use it... | |
389 | ||
390 | - actually, gnutls_x509_privkey_import() appears to require a curve name parameter | |
391 | value for that is an OID? a local-only integer (it's an enum in GnuTLS)? | |
392 | ||
393 | ||
394 | Useful cmds: | |
395 | ssh-keygen -t ecdsa -f foo.privkey | |
396 | ssh-keygen -t ecdsa -b384 -f foo.privkey | |
397 | ssh-keygen -t ecdsa -b521 -f foo.privkey | |
398 | ssh-keygen -t ed25519 -f foo.privkey | |
399 | ||
400 | < foo openssl pkcs8 -in /dev/stdin -inform PEM -nocrypt -topk8 -outform DER | od -x | |
401 | ||
402 | openssl asn1parse -in foo -inform PEM -dump | |
403 | openssl asn1parse -in foo -inform PEM -dump -stroffset 24 (??) | |
404 | (not good for ed25519) | |
405 | ||
2592e6c0 | 406 | */ |
f9ba5e22 | 407 | |
2592e6c0 JH |
408 | if ( !(s1 = Ustrstr(CS privkey_pem, "-----BEGIN RSA PRIVATE KEY-----")) |
409 | || !(s2 = Ustrstr(CS (s1+=31), "-----END RSA PRIVATE KEY-----" )) | |
410 | ) | |
411 | return US"Bad PEM wrapper"; | |
412 | ||
413 | *s2 = '\0'; | |
414 | ||
428cdca7 | 415 | if ((rc = b64decode(s1, &der.data) < 0)) |
2592e6c0 | 416 | return US"Bad PEM-DER b64 decode"; |
428cdca7 | 417 | der.len = rc; |
2592e6c0 JH |
418 | |
419 | /* untangle asn.1 */ | |
420 | ||
421 | /* sequence; just move past the header */ | |
422 | if ((rc = as_tag(&der, ASN1_CLASS_STRUCTURED, ASN1_TAG_SEQUENCE, NULL)) | |
423 | != ASN1_SUCCESS) goto asn_err; | |
424 | ||
425 | /* integer version; move past the header, check is zero */ | |
426 | if ((rc = as_tag(&der, 0, ASN1_TAG_INTEGER, &alen)) != ASN1_SUCCESS) | |
427 | goto asn_err; | |
428 | if (alen != 1 || *der.data != 0) | |
429 | return US"Bad version number"; | |
430 | der.data++; der.len--; | |
431 | ||
432 | if ( (s1 = as_mpi(&der, &sign_ctx->n)) | |
433 | || (s1 = as_mpi(&der, &sign_ctx->e)) | |
434 | || (s1 = as_mpi(&der, &sign_ctx->d)) | |
435 | || (s1 = as_mpi(&der, &sign_ctx->p)) | |
436 | || (s1 = as_mpi(&der, &sign_ctx->q)) | |
437 | || (s1 = as_mpi(&der, &sign_ctx->dp)) | |
438 | || (s1 = as_mpi(&der, &sign_ctx->dq)) | |
439 | || (s1 = as_mpi(&der, &sign_ctx->qp)) | |
440 | ) | |
441 | return s1; | |
442 | ||
349d0869 | 443 | #ifdef extreme_debug |
6e4aaa85 | 444 | DEBUG(D_acl) debug_printf_indent("rsa_signing_init:\n"); |
2592e6c0 JH |
445 | { |
446 | uschar * s; | |
447 | gcry_mpi_aprint (GCRYMPI_FMT_HEX, &s, NULL, sign_ctx->n); | |
6e4aaa85 | 448 | debug_printf_indent(" N : %s\n", s); |
2592e6c0 | 449 | gcry_mpi_aprint (GCRYMPI_FMT_HEX, &s, NULL, sign_ctx->e); |
6e4aaa85 | 450 | debug_printf_indent(" E : %s\n", s); |
2592e6c0 | 451 | gcry_mpi_aprint (GCRYMPI_FMT_HEX, &s, NULL, sign_ctx->d); |
6e4aaa85 | 452 | debug_printf_indent(" D : %s\n", s); |
2592e6c0 | 453 | gcry_mpi_aprint (GCRYMPI_FMT_HEX, &s, NULL, sign_ctx->p); |
6e4aaa85 | 454 | debug_printf_indent(" P : %s\n", s); |
2592e6c0 | 455 | gcry_mpi_aprint (GCRYMPI_FMT_HEX, &s, NULL, sign_ctx->q); |
6e4aaa85 | 456 | debug_printf_indent(" Q : %s\n", s); |
2592e6c0 | 457 | gcry_mpi_aprint (GCRYMPI_FMT_HEX, &s, NULL, sign_ctx->dp); |
6e4aaa85 | 458 | debug_printf_indent(" DP: %s\n", s); |
2592e6c0 | 459 | gcry_mpi_aprint (GCRYMPI_FMT_HEX, &s, NULL, sign_ctx->dq); |
6e4aaa85 | 460 | debug_printf_indent(" DQ: %s\n", s); |
2592e6c0 | 461 | gcry_mpi_aprint (GCRYMPI_FMT_HEX, &s, NULL, sign_ctx->qp); |
6e4aaa85 | 462 | debug_printf_indent(" QP: %s\n", s); |
2592e6c0 | 463 | } |
349d0869 | 464 | #endif |
286b9d5f JH |
465 | |
466 | sign_ctx->keytype = KEYTYPE_RSA; | |
2592e6c0 JH |
467 | return NULL; |
468 | ||
469 | asn_err: return US asn1_strerror(rc); | |
470 | } | |
471 | ||
472 | ||
473 | ||
474 | /* allocate mem for signature (when signing) */ | |
286b9d5f | 475 | /* sign already-hashed data. |
2592e6c0 JH |
476 | |
477 | Return: NULL for success, or an error string */ | |
478 | ||
479 | const uschar * | |
d73e45df | 480 | exim_dkim_sign(es_ctx * sign_ctx, hashmethod hash, blob * data, blob * sig) |
2592e6c0 | 481 | { |
349d0869 | 482 | char * sexp_hash; |
2592e6c0 JH |
483 | gcry_sexp_t s_hash = NULL, s_key = NULL, s_sig = NULL; |
484 | gcry_mpi_t m_sig; | |
485 | uschar * errstr; | |
486 | gcry_error_t gerr; | |
487 | ||
9b2583c4 JH |
488 | /*XXX will need extension for hash types (though, possibly, should |
489 | be re-specced to not rehash but take an already-hashed value? Actually | |
d73e45df | 490 | current impl looks WRONG - it _is_ given a hash so should not be |
9b2583c4 JH |
491 | re-hashing. Has this been tested? |
492 | ||
493 | Will need extension for non-RSA sugning algos. */ | |
494 | ||
d73e45df JH |
495 | switch (hash) |
496 | { | |
349d0869 JH |
497 | case HASH_SHA1: sexp_hash = "(data(flags pkcs1)(hash sha1 %b))"; break; |
498 | case HASH_SHA2_256: sexp_hash = "(data(flags pkcs1)(hash sha256 %b))"; break; | |
d73e45df JH |
499 | default: return US"nonhandled hash type"; |
500 | } | |
501 | ||
2592e6c0 | 502 | #define SIGSPACE 128 |
f3ebb786 | 503 | sig->data = store_get(SIGSPACE, FALSE); |
2592e6c0 JH |
504 | |
505 | if (gcry_mpi_cmp (sign_ctx->p, sign_ctx->q) > 0) | |
506 | { | |
507 | gcry_mpi_swap (sign_ctx->p, sign_ctx->q); | |
508 | gcry_mpi_invm (sign_ctx->qp, sign_ctx->p, sign_ctx->q); | |
509 | } | |
510 | ||
511 | if ( (gerr = gcry_sexp_build (&s_key, NULL, | |
512 | "(private-key (rsa (n%m)(e%m)(d%m)(p%m)(q%m)(u%m)))", | |
513 | sign_ctx->n, sign_ctx->e, | |
514 | sign_ctx->d, sign_ctx->p, | |
515 | sign_ctx->q, sign_ctx->qp)) | |
349d0869 | 516 | || (gerr = gcry_sexp_build (&s_hash, NULL, sexp_hash, |
2592e6c0 JH |
517 | (int) data->len, CS data->data)) |
518 | || (gerr = gcry_pk_sign (&s_sig, s_hash, s_key)) | |
519 | ) | |
520 | return US gcry_strerror(gerr); | |
521 | ||
522 | /* gcry_sexp_dump(s_sig); */ | |
523 | ||
524 | if ( !(s_sig = gcry_sexp_find_token(s_sig, "s", 0)) | |
525 | ) | |
526 | return US"no sig result"; | |
527 | ||
528 | m_sig = gcry_sexp_nth_mpi(s_sig, 1, GCRYMPI_FMT_USG); | |
529 | ||
349d0869 | 530 | #ifdef extreme_debug |
2592e6c0 JH |
531 | DEBUG(D_acl) |
532 | { | |
533 | uschar * s; | |
534 | gcry_mpi_aprint (GCRYMPI_FMT_HEX, &s, NULL, m_sig); | |
6e4aaa85 | 535 | debug_printf_indent(" SG: %s\n", s); |
2592e6c0 | 536 | } |
349d0869 | 537 | #endif |
2592e6c0 JH |
538 | |
539 | gerr = gcry_mpi_print(GCRYMPI_FMT_USG, sig->data, SIGSPACE, &sig->len, m_sig); | |
540 | if (gerr) | |
541 | { | |
6e4aaa85 | 542 | debug_printf_indent("signature conversion from MPI to buffer failed\n"); |
2592e6c0 JH |
543 | return US gcry_strerror(gerr); |
544 | } | |
545 | #undef SIGSPACE | |
546 | ||
547 | return NULL; | |
548 | } | |
549 | ||
550 | ||
286b9d5f | 551 | /* import public key (from blob in memory) |
2592e6c0 JH |
552 | Return: NULL for success, or an error string */ |
553 | ||
554 | const uschar * | |
286b9d5f | 555 | exim_dkim_verify_init(blob * pubkey, keyformat fmt, ev_ctx * verify_ctx) |
2592e6c0 JH |
556 | { |
557 | /* | |
558 | in code sequence per b81207d2bfa92 rsa_parse_public_key() and asn1_get_mpi() | |
559 | */ | |
560 | uschar tag_class; | |
561 | int taglen; | |
562 | long alen; | |
563 | int rc; | |
564 | uschar * errstr; | |
565 | gcry_error_t gerr; | |
566 | uschar * stage = US"S1"; | |
567 | ||
286b9d5f JH |
568 | if (fmt != KEYFMT_DER) return US"pubkey format not handled"; |
569 | ||
2592e6c0 JH |
570 | /* |
571 | sequence | |
572 | sequence | |
573 | OBJECT:rsaEncryption | |
574 | NULL | |
575 | BIT STRING:RSAPublicKey | |
576 | sequence | |
577 | INTEGER:Public modulus | |
578 | INTEGER:Public exponent | |
579 | ||
580 | openssl rsa -in aux-fixed/dkim/dkim.private -pubout -outform DER | od -t x1 | head; | |
581 | openssl rsa -in aux-fixed/dkim/dkim.private -pubout | openssl asn1parse -dump; | |
582 | openssl rsa -in aux-fixed/dkim/dkim.private -pubout | openssl asn1parse -dump -offset 22; | |
583 | */ | |
584 | ||
585 | /* sequence; just move past the header */ | |
286b9d5f | 586 | if ((rc = as_tag(pubkey, ASN1_CLASS_STRUCTURED, ASN1_TAG_SEQUENCE, NULL)) |
2592e6c0 JH |
587 | != ASN1_SUCCESS) goto asn_err; |
588 | ||
589 | /* sequence; skip the entire thing */ | |
590 | DEBUG(D_acl) stage = US"S2"; | |
286b9d5f | 591 | if ((rc = as_tag(pubkey, ASN1_CLASS_STRUCTURED, ASN1_TAG_SEQUENCE, &alen)) |
2592e6c0 | 592 | != ASN1_SUCCESS) goto asn_err; |
286b9d5f | 593 | pubkey->data += alen; pubkey->len -= alen; |
2592e6c0 JH |
594 | |
595 | ||
596 | /* bitstring: limit range to size of bitstring; | |
597 | move over header + content wrapper */ | |
598 | DEBUG(D_acl) stage = US"BS"; | |
286b9d5f | 599 | if ((rc = as_tag(pubkey, 0, ASN1_TAG_BIT_STRING, &alen)) != ASN1_SUCCESS) |
2592e6c0 | 600 | goto asn_err; |
286b9d5f JH |
601 | pubkey->len = alen; |
602 | pubkey->data++; pubkey->len--; | |
2592e6c0 JH |
603 | |
604 | /* sequence; just move past the header */ | |
605 | DEBUG(D_acl) stage = US"S3"; | |
286b9d5f | 606 | if ((rc = as_tag(pubkey, ASN1_CLASS_STRUCTURED, ASN1_TAG_SEQUENCE, NULL)) |
2592e6c0 JH |
607 | != ASN1_SUCCESS) goto asn_err; |
608 | ||
609 | /* read two integers */ | |
610 | DEBUG(D_acl) stage = US"MPI"; | |
286b9d5f JH |
611 | if ( (errstr = as_mpi(pubkey, &verify_ctx->n)) |
612 | || (errstr = as_mpi(pubkey, &verify_ctx->e)) | |
2592e6c0 JH |
613 | ) |
614 | return errstr; | |
615 | ||
349d0869 | 616 | #ifdef extreme_debug |
6e4aaa85 | 617 | DEBUG(D_acl) debug_printf_indent("rsa_verify_init:\n"); |
2592e6c0 JH |
618 | { |
619 | uschar * s; | |
620 | gcry_mpi_aprint (GCRYMPI_FMT_HEX, &s, NULL, verify_ctx->n); | |
6e4aaa85 | 621 | debug_printf_indent(" N : %s\n", s); |
2592e6c0 | 622 | gcry_mpi_aprint (GCRYMPI_FMT_HEX, &s, NULL, verify_ctx->e); |
6e4aaa85 | 623 | debug_printf_indent(" E : %s\n", s); |
2592e6c0 JH |
624 | } |
625 | ||
349d0869 | 626 | #endif |
2592e6c0 JH |
627 | return NULL; |
628 | ||
629 | asn_err: | |
630 | DEBUG(D_acl) return string_sprintf("%s: %s", stage, asn1_strerror(rc)); | |
631 | return US asn1_strerror(rc); | |
632 | } | |
633 | ||
634 | ||
286b9d5f JH |
635 | /* verify signature (of hash) |
636 | XXX though we appear to be doing a hash, too! | |
637 | (given pubkey & alleged sig) | |
2592e6c0 JH |
638 | Return: NULL for success, or an error string */ |
639 | ||
640 | const uschar * | |
d73e45df | 641 | exim_dkim_verify(ev_ctx * verify_ctx, hashmethod hash, blob * data_hash, blob * sig) |
2592e6c0 JH |
642 | { |
643 | /* | |
644 | cf. libgnutls 2.8.5 _wrap_gcry_pk_verify() | |
645 | */ | |
349d0869 | 646 | char * sexp_hash; |
2592e6c0 JH |
647 | gcry_mpi_t m_sig; |
648 | gcry_sexp_t s_sig = NULL, s_hash = NULL, s_pkey = NULL; | |
649 | gcry_error_t gerr; | |
650 | uschar * stage; | |
651 | ||
349d0869 | 652 | /*XXX needs extension for SHA512 */ |
d73e45df JH |
653 | switch (hash) |
654 | { | |
349d0869 JH |
655 | case HASH_SHA1: sexp_hash = "(data(flags pkcs1)(hash sha1 %b))"; break; |
656 | case HASH_SHA2_256: sexp_hash = "(data(flags pkcs1)(hash sha256 %b))"; break; | |
657 | default: return US"nonhandled hash type"; | |
d73e45df JH |
658 | } |
659 | ||
2592e6c0 JH |
660 | if ( (stage = US"pkey sexp build", |
661 | gerr = gcry_sexp_build (&s_pkey, NULL, "(public-key(rsa(n%m)(e%m)))", | |
662 | verify_ctx->n, verify_ctx->e)) | |
663 | || (stage = US"data sexp build", | |
349d0869 | 664 | gerr = gcry_sexp_build (&s_hash, NULL, sexp_hash, |
2592e6c0 JH |
665 | (int) data_hash->len, CS data_hash->data)) |
666 | || (stage = US"sig mpi scan", | |
667 | gerr = gcry_mpi_scan(&m_sig, GCRYMPI_FMT_USG, sig->data, sig->len, NULL)) | |
668 | || (stage = US"sig sexp build", | |
669 | gerr = gcry_sexp_build (&s_sig, NULL, "(sig-val(rsa(s%m)))", m_sig)) | |
670 | || (stage = US"verify", | |
671 | gerr = gcry_pk_verify (s_sig, s_hash, s_pkey)) | |
672 | ) | |
673 | { | |
6e4aaa85 | 674 | DEBUG(D_acl) debug_printf_indent("verify: error in stage '%s'\n", stage); |
2592e6c0 JH |
675 | return US gcry_strerror(gerr); |
676 | } | |
677 | ||
678 | if (s_sig) gcry_sexp_release (s_sig); | |
679 | if (s_hash) gcry_sexp_release (s_hash); | |
680 | if (s_pkey) gcry_sexp_release (s_pkey); | |
681 | gcry_mpi_release (m_sig); | |
682 | gcry_mpi_release (verify_ctx->n); | |
683 | gcry_mpi_release (verify_ctx->e); | |
684 | ||
685 | return NULL; | |
686 | } | |
687 | ||
688 | ||
689 | ||
690 | ||
d73e45df | 691 | #elif defined(SIGN_OPENSSL) |
2592e6c0 JH |
692 | /******************************************************************************/ |
693 | ||
694 | void | |
9b2583c4 | 695 | exim_dkim_init(void) |
2592e6c0 | 696 | { |
9e70917d | 697 | ERR_load_crypto_strings(); |
2592e6c0 JH |
698 | } |
699 | ||
700 | ||
617d3932 | 701 | /* accumulate data (was gnutls-only but now needed for OpenSSL non-EC too |
286b9d5f | 702 | because now using hash-and-sign interface) */ |
acec9514 JH |
703 | gstring * |
704 | exim_dkim_data_append(gstring * g, uschar * s) | |
2592e6c0 | 705 | { |
286b9d5f | 706 | return string_cat(g, s); |
2592e6c0 JH |
707 | } |
708 | ||
709 | ||
710 | /* import private key from PEM string in memory. | |
711 | Return: NULL for success, or an error string */ | |
712 | ||
713 | const uschar * | |
617d3932 | 714 | exim_dkim_signing_init(const uschar * privkey_pem, es_ctx * sign_ctx) |
2592e6c0 | 715 | { |
d70fc283 | 716 | BIO * bp = BIO_new_mem_buf((void *)privkey_pem, -1); |
2592e6c0 | 717 | |
d73e45df | 718 | if (!(sign_ctx->key = PEM_read_bio_PrivateKey(bp, NULL, NULL, NULL))) |
c59b09dc JH |
719 | return string_sprintf("privkey PEM-block import: %s", |
720 | ERR_error_string(ERR_get_error(), NULL)); | |
286b9d5f JH |
721 | |
722 | sign_ctx->keytype = | |
723 | #ifdef SIGN_HAVE_ED25519 | |
cb78c1a8 | 724 | EVP_PKEY_type(EVP_PKEY_id(sign_ctx->key)) == EVP_PKEY_ED25519 |
286b9d5f JH |
725 | ? KEYTYPE_ED25519 : KEYTYPE_RSA; |
726 | #else | |
727 | KEYTYPE_RSA; | |
728 | #endif | |
2592e6c0 JH |
729 | return NULL; |
730 | } | |
731 | ||
732 | ||
733 | ||
734 | /* allocate mem for signature (when signing) */ | |
cb78c1a8 | 735 | /* hash & sign data. Incremental not supported. |
2592e6c0 | 736 | |
9e70917d | 737 | Return: NULL for success with the signaature in the sig blob, or an error string */ |
2592e6c0 JH |
738 | |
739 | const uschar * | |
d73e45df | 740 | exim_dkim_sign(es_ctx * sign_ctx, hashmethod hash, blob * data, blob * sig) |
2592e6c0 | 741 | { |
d73e45df | 742 | const EVP_MD * md; |
286b9d5f | 743 | EVP_MD_CTX * ctx; |
d73e45df | 744 | size_t siglen; |
9b2583c4 | 745 | |
d73e45df JH |
746 | switch (hash) |
747 | { | |
cb78c1a8 | 748 | case HASH_NULL: md = NULL; break; /* Ed25519 signing */ |
d73e45df JH |
749 | case HASH_SHA1: md = EVP_sha1(); break; |
750 | case HASH_SHA2_256: md = EVP_sha256(); break; | |
751 | case HASH_SHA2_512: md = EVP_sha512(); break; | |
752 | default: return US"nonhandled hash type"; | |
753 | } | |
2592e6c0 | 754 | |
cb78c1a8 JH |
755 | #ifdef SIGN_HAVE_ED25519 |
756 | if ( (ctx = EVP_MD_CTX_new()) | |
757 | && EVP_DigestSignInit(ctx, NULL, md, NULL, sign_ctx->key) > 0 | |
758 | && EVP_DigestSign(ctx, NULL, &siglen, NULL, 0) > 0 | |
f3ebb786 | 759 | && (sig->data = store_get(siglen, FALSE)) |
f9ba5e22 | 760 | |
cb78c1a8 | 761 | /* Obtain the signature (slen could change here!) */ |
39e02651 | 762 | && EVP_DigestSign(ctx, sig->data, &siglen, data->data, data->len) > 0 |
cb78c1a8 JH |
763 | ) |
764 | { | |
765 | EVP_MD_CTX_destroy(ctx); | |
766 | sig->len = siglen; | |
767 | return NULL; | |
768 | } | |
769 | #else | |
770 | /*XXX renamed to EVP_MD_CTX_new() in 1.1.0 */ | |
771 | if ( (ctx = EVP_MD_CTX_create()) | |
772 | && EVP_DigestSignInit(ctx, NULL, md, NULL, sign_ctx->key) > 0 | |
286b9d5f | 773 | && EVP_DigestSignUpdate(ctx, data->data, data->len) > 0 |
286b9d5f | 774 | && EVP_DigestSignFinal(ctx, NULL, &siglen) > 0 |
f3ebb786 | 775 | && (sig->data = store_get(siglen, FALSE)) |
cb78c1a8 JH |
776 | |
777 | /* Obtain the signature (slen could change here!) */ | |
286b9d5f | 778 | && EVP_DigestSignFinal(ctx, sig->data, &siglen) > 0 |
d73e45df | 779 | ) |
2592e6c0 | 780 | { |
286b9d5f JH |
781 | EVP_MD_CTX_destroy(ctx); |
782 | sig->len = siglen; | |
783 | return NULL; | |
2592e6c0 | 784 | } |
cb78c1a8 | 785 | #endif |
2592e6c0 | 786 | |
286b9d5f | 787 | if (ctx) EVP_MD_CTX_destroy(ctx); |
7845dbb3 | 788 | return US ERR_error_string(ERR_get_error(), NULL); |
2592e6c0 JH |
789 | } |
790 | ||
791 | ||
792 | ||
286b9d5f | 793 | /* import public key (from blob in memory) |
9b2583c4 | 794 | Return: NULL for success, or an error string */ |
2592e6c0 JH |
795 | |
796 | const uschar * | |
286b9d5f | 797 | exim_dkim_verify_init(blob * pubkey, keyformat fmt, ev_ctx * verify_ctx) |
2592e6c0 | 798 | { |
286b9d5f JH |
799 | const uschar * s = pubkey->data; |
800 | uschar * ret = NULL; | |
2592e6c0 | 801 | |
286b9d5f JH |
802 | switch(fmt) |
803 | { | |
804 | case KEYFMT_DER: | |
286b9d5f JH |
805 | /*XXX hmm, we never free this */ |
806 | if (!(verify_ctx->key = d2i_PUBKEY(NULL, &s, pubkey->len))) | |
807 | ret = US ERR_error_string(ERR_get_error(), NULL); | |
808 | break; | |
809 | #ifdef SIGN_HAVE_ED25519 | |
810 | case KEYFMT_ED25519_BARE: | |
cb78c1a8 JH |
811 | if (!(verify_ctx->key = EVP_PKEY_new_raw_public_key(EVP_PKEY_ED25519, NULL, |
812 | s, pubkey->len))) | |
286b9d5f | 813 | ret = US ERR_error_string(ERR_get_error(), NULL); |
286b9d5f JH |
814 | break; |
815 | #endif | |
816 | default: | |
817 | ret = US"pubkey format not handled"; | |
818 | break; | |
819 | } | |
9b2583c4 | 820 | |
286b9d5f | 821 | return ret; |
2592e6c0 JH |
822 | } |
823 | ||
824 | ||
825 | ||
826 | ||
cb78c1a8 | 827 | /* verify signature (of hash, except Ed25519 where of-data) |
286b9d5f | 828 | (given pubkey & alleged sig) |
2592e6c0 JH |
829 | Return: NULL for success, or an error string */ |
830 | ||
831 | const uschar * | |
286b9d5f | 832 | exim_dkim_verify(ev_ctx * verify_ctx, hashmethod hash, blob * data, blob * sig) |
2592e6c0 | 833 | { |
d73e45df | 834 | const EVP_MD * md; |
286b9d5f | 835 | |
d73e45df | 836 | switch (hash) |
2592e6c0 | 837 | { |
cb78c1a8 | 838 | case HASH_NULL: md = NULL; break; |
d73e45df JH |
839 | case HASH_SHA1: md = EVP_sha1(); break; |
840 | case HASH_SHA2_256: md = EVP_sha256(); break; | |
841 | case HASH_SHA2_512: md = EVP_sha512(); break; | |
842 | default: return US"nonhandled hash type"; | |
2592e6c0 | 843 | } |
d73e45df | 844 | |
cb78c1a8 JH |
845 | #ifdef SIGN_HAVE_ED25519 |
846 | if (!md) | |
286b9d5f JH |
847 | { |
848 | EVP_MD_CTX * ctx; | |
d73e45df | 849 | |
c8b2f374 JH |
850 | if ((ctx = EVP_MD_CTX_new())) |
851 | { | |
852 | if ( EVP_DigestVerifyInit(ctx, NULL, md, NULL, verify_ctx->key) > 0 | |
853 | && EVP_DigestVerify(ctx, sig->data, sig->len, data->data, data->len) > 0 | |
854 | ) | |
855 | { EVP_MD_CTX_free(ctx); return NULL; } | |
856 | EVP_MD_CTX_free(ctx); | |
857 | } | |
286b9d5f | 858 | } |
cb78c1a8 JH |
859 | else |
860 | #endif | |
286b9d5f JH |
861 | { |
862 | EVP_PKEY_CTX * ctx; | |
863 | ||
c8b2f374 | 864 | if ((ctx = EVP_PKEY_CTX_new(verify_ctx->key, NULL))) |
25fa0868 | 865 | { |
c8b2f374 JH |
866 | if ( EVP_PKEY_verify_init(ctx) > 0 |
867 | && EVP_PKEY_CTX_set_rsa_padding(ctx, RSA_PKCS1_PADDING) > 0 | |
868 | && EVP_PKEY_CTX_set_signature_md(ctx, md) > 0 | |
869 | && EVP_PKEY_verify(ctx, sig->data, sig->len, | |
870 | data->data, data->len) == 1 | |
25fa0868 JH |
871 | ) |
872 | { EVP_PKEY_CTX_free(ctx); return NULL; } | |
25fa0868 | 873 | EVP_PKEY_CTX_free(ctx); |
c8b2f374 JH |
874 | |
875 | DEBUG(D_tls) | |
876 | if (Ustrcmp(ERR_reason_error_string(ERR_peek_error()), "wrong signature length") == 0) | |
877 | debug_printf("sig len (from msg hdr): %d, expected (from dns pubkey) %d\n", | |
878 | (int) sig->len, EVP_PKEY_size(verify_ctx->key)); | |
25fa0868 | 879 | } |
286b9d5f | 880 | } |
c8b2f374 JH |
881 | |
882 | return US ERR_error_string(ERR_get_error(), NULL); | |
2592e6c0 JH |
883 | } |
884 | ||
885 | ||
d73e45df | 886 | |
2592e6c0 JH |
887 | #endif |
888 | /******************************************************************************/ | |
889 | ||
890 | #endif /*DISABLE_DKIM*/ | |
260958d6 | 891 | #endif /*MACRO_PREDEF*/ |
2592e6c0 | 892 | /* End of File */ |